The following sections describe how to use the tree control and tree view classes.

14.8.1 To create a tree control in a dialog

1. In the Visual Studio resource editor, create a tree control resource on the dialog resource.

2. Instantiate an SECTreeCtrl object as a member of your dialog class.

3. In the OnInitDialog() method of your dialog class, call SubclassTreeCtrlId() on the SECTreeCtrl instance. For example:

   m_pTreeCtrl->SubclassTreeCtrlId( IDC_TREE, this );

14.8.2 To create a tree control dynamically

1. Create a unique control ID for the tree control. In Visual Studio, you can create an ID with the Resource Includes dialog.

2. Instantiate an SECTreeCtrl object.

3. Call the Create() method and specify the desired styles, rectangle, and parent. For example:

   DWORD dwStyle = TVS_SHOWSELALWAYS | TVS_HASBUTTONS | TVS_LINESATROOT | TVS_HASLINES | TVS_EDITLABELS | TVS_SHOWSELALWAYS | TVS_DISABLEDRAGDROP | WS_CHILD | WS_VISIBLE; DWORD dwStyleEx = TVXS_MULTISEL | TVXS_FLYBYTOOLTIPS | LVXS_HILIGHTSUBITEMS; m_pTreeCtrl->Create( dwStyle, dwStyleEx, rect, this, IDC_TREE);

4. If you are creating a tree control inside a control bar or other resizable window, remember to override the OnSize() method to resize the tree control with the parent window.

   void CMyControlBar::OnSize(UINT nType, int cx, int cy) { SECControlBar::OnSize(nType, cx, cy); if ( ::IsWindow(m_tree) ) m_tree.SetWindowPos( NULL, 0, 0, cx, cy, SWP_NOMOVE | SWP_NOACTIVATE | SWP_NOZORDER ); }

14.8.3 To add a tree item

14.8.4 To create multiple columns

1. Call the InsertColumn() method.

   m_pTreeCtrl->InsertColumn( 1 /*0-based column index*/, "Attendance", LVCFMT_CENTER, 40 /*width*/ ); m_pTreeCtrl->InsertColumn( 2 /*0-based column index*/, "Grade", LVCFMT_CENTER, 40 /*width*/ );

2. If you want, you can mark all items as needing a remeasurement when a WM_PAINT occurs, and invalidate the control.

   m_pTreeCtrlX->ReMeasureAllItems(); m_pTreeCtrlX->Invalidate();

14.8.5 To set the text on subitems of multi-column trees

In trees with multiple columns, the objects called subitems are managed by the items of the tree (in column 0). These subitems control what is displayed in the additional columns.

Method 1

1. Handle the LVN_GETDISPINFO notification.

2. In the handler for the LVN_GETDISPINFO notification, manage the subitem text storage yourself and then provide it to the control on demand via the callback.

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   This is the default method demonstrated in the TREEDEMO sample. This method provides maximum performance in large trees with many columns of data.

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Method 2

1. Call StoreSubItemText(TRUE) after creation to enable the tree control to manage subitem text storage for you.

2. Call the SetItemText() or SetItemString() methods to set the text directly.

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   This is an easier approach than using the callback method, but it is not as scalable for large trees when performance is an issue. This method is demonstrated in the STATE sample.

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14.8.6 To create a standard image list for tree items

Call the SetImageList() method.

SetImageList( CImageList*, TVSIL_NORMAL);

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Use of an image list is optional. If state images are also associated with a tree item, you can assign them different widths than the standard image, but not different heights.

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14.8.7 To create a state image list for tree items

14.8.8 To create a tree item with a state image

14.8.9 To change a state image on a tree item

14.8.10 To add an overlay image to a tree item

1. Obtain a HTREEITEM handle for the tree item. For example:

   HTREEITEM hti = m_tree.InsertItem(&tvi);

2. Instantiate a TV_ITEM structure and update the members for the desired overlay image.

   TV_ITEM tvi; tvi.hItem = hti; tvi.mask = TVIF_HANDLE | TVIF_STATE; tvi.stateMask = TVIS_OVERLAYMASK; tvi.state = INDEXTOOVERLAYMASK( iImage );

3. Call the SetItem() method using the TV_ITEM as a parameter.

   m_secTree.SetItem( &tvi );

14.8.11 To find out which items are selected

Call the GetSelectionArray() method.

pArrSelected = m_secTree.GetSelectionArray();

14.8.12 To specify different colors for tree items

1. Override PickTextColor().

2. In the PickTextColor() override, assign the rgbText member of the LvPaintContext structure supplied as a parameter. For example, the following code is in the Objective Toolkit Build Wizard.

   void CMyTreeView::PickTextColors(LvPaintContext* pPC) { ASSERT(pPC); SECTreeView::PickTextColors(pPC); if(pPC->lvi.iSubItem == 0) // subitem (column) number 0 { // Inside tree column, get a convenient context. TvPaintContext* pTvPC = (TvPaintContext*)pPC; // Check the properties of tree item (pTvPC->tvi), // and change color accordingly. For example, // to change the color of root nodes: HTREEITEM hParent=GetParentItem(pTvPC->tvi.hItem); if(hParent == NULL) { pTvPC->rgbText= m_rootColor; if ( GetFocus()== this && (pTvPC->lvi.state & LVIS_SELECTED) ) pTvPC->rgbTextBkgnd = RGB(255, 255, 0); // highlight } } }

14.8.13 To specify different fonts for tree items

1. Override the PickTextFont() method.

2. In the PickTextFont() override, assign the pFont member of the LvPaintContext structure supplied as a parameter. For example, the following code is in the Objective Toolkit Build Wizard.

   void CMyTreeView::PickTextFont(LvPaintContext* pPC) { ASSERT(pPC); SECTreeView::PickTextFont(pPC); if(pPC->lvi.iSubItem == 0) // subitem (column) number 0 { // Inside tree column, get a convenient context. TvPaintContext* pTvPC = (TvPaintContext*)pPC; // Check the properties of tree item (pTvPC->tvi), // and change font accordingly. For example, // to change the font of root nodes: HTREEITEM hParent=GetParentItem(pTvPC->tvi.hItem); if(hParent == NULL) pTvPC->pFont= &m_fontRoot; } }

14.8.14 To update the tree control

14.8.15 To incorporate SECTreeCtrl into an application already using CtreeCtrl

In the header file, locate your instance of CTreeCtrl.

1. Change this from CTreeCtrl to SECTreeCtrl.

2. Population of the tree is the same as for CTreeCtrl.

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   SECTreeCtrl is for the most part drop-in compatible with the CTreeCtrl, but not when you start changing or adding behaviors such as drag scrolling.

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